The present invention pertains generally to bearing construction for a live shaft with radial and thrust loads borne by a ball element.
In the food processing industry, machines are utilized to remove husks and debris from food articles. Such machines utilize pairs of counter rotating powered shafts, each shaft equipped with tubular rolls. Such cooperating shafts are driven at high speed and encounter substantial loads as the rolls engage the food article. Typically in a husking machine operation ears of corn are continuously deposited on the powered shafts in random fashion with the counter rotating shafts and husking rolls thereon stripping away the husks by a pinching action. Similar machines are used in other food processing efforts, as for example, in the stripping of stems from citrus fruit. A husking machine is shown in U.S. Pat. No. 4,278,097 incorporated herein by reference.
Banks of such machines are used in large food processing plants and during harvest time operate three work shifts six or seven days a week. Additionally, the problem of wear is accentuated by the environment in which the machines operate, e.g., both moisture and grit act on shaft and bearing surfaces. The shut down of such a machine at peak harvest time is particularly undesirable as a backlog readily occurs in product flow with loss of production and man hours.
Another factor in the wear of shafts and bearings of husking machines is that the shafts carrying the husking rolls operate in an inclined position with the shaft ends encountering substantial thrust loads. To alleviate wear of machines equipped with prior art type bearing assemblies shaft speed is below the optimum from a production standpoint to reduce the number of costly shutdowns for maintenance and/or repairs. Additionally, prior art bearing arrangements do not lend themselves to precise, convenient adjustment to permit avoidance of shaft play. The use of thrust washers on such shafts is only a partial remedy and results in the disassembly of the shaft and supporting bearings for periodic thrust washer replacement. Helical lands on the husking rolls contribute to axial loading of the roll equipped shafts.
In the citrus industry similar machines are used to remove stems with cooperating rolls on parallel shafts being ideally in pressure free contact to affect efficient removal of stems, etc., from the fruit. Any play in the roll shaft bearings permits pinching and pulling of the debris being removed resulting in roll and gear wear as opposed to debris removal by a biting action of the rolls.
The prior art includes U.S. Pat. No. 4,865,529 which discloses a main shaft of a turbine and turbopump assembly with ball elements axially disposed at the shaft ends. U.S. Pat. Nos. 405,559; 931,069; 935,452; 1,088,839; 2,127,196; 4,265,498; 4,618,273 and 4,805,432 disclose shaft bearings having an axially disposed ball element, some with a screw type adjustment.